Components for setting a scan-integrated illumination energy in an object plane of a microlithography projection exposure apparatus are known for example from EP0952491A2 and US 2006/0244941.
Microlithography projection exposure apparatuses used for producing microelectronic components include, among other things, a light source, an illumination system for illuminating a structure-bearing mask (the so-called reticle), and a projection optical unit for imaging the mask onto a substrate (wafer). The substrate contains a photosensitive layer, which is chemically altered by the application of a radiation dose. In this case, the reticle is arranged in the object plane and the wafer is arranged in the image plane of the projection optical unit of the microlithography projection exposure apparatus. In this case, the optical components of the illumination system and of the projection optical unit can be either refractive or reflective components. Combinations of refractive and reflective components are also possible. Likewise, the reticle can be embodied in either reflective or transmissive fashion. Such apparatuses generally are formed completely of reflective components particularly when they are operated with a radiation having a wavelength of less than approximately 100 nm.
Microlithography projection exposure apparatuses are often operated as so-called scanners. This means that the reticle is moved through a slotted illumination field along a scan direction, while the wafer is correspondingly moved in the image plane of the projection optical unit. The ratio of the speeds of wafer to reticle corresponds to the magnification of the projection optical unit between reticle and wafer, which is usually less than 1. Since the chemical alteration of the photosensitive layer often takes place to a sufficient extent only after a specific radiation dose has been administered, it is often desirable to ensure that all regions of the wafer which are intended to be exposed receive the same radiation energy. Non-uniformities in the distribution of the radiation energy in the object plane can lead to variations in the feature size since the position of the edges of structures to be exposed depends on whether or not the desired radiation energy for exposure was attained. Specific components are used in order to compensate for non-uniformities in the distribution of the radiation energy. One such component can include, for example, two mutually opposite arrangements of identical, vignetting, finger-like diaphragms which adjoin one another and are oriented substantially parallel to the scan direction. Each of these diaphragms is moveable for example in the scan direction, such that the distance between ends of a diaphragm pair which lie opposite one another in the scan direction can be set. It is thus possible to provide a slotted illumination field in the object plane, the field having a varying width in the scan direction along the direction perpendicular to the scan direction. Since the radiation energy is integrated along the scan direction on account of the scan process, the scan-integrated radiation energy desired for chemically altering the photosensitive layer can be set in a targeted manner. Those edges of the diaphragms which delimit the illumination field thus function as upper and lower integration limits. Such edges are referred to hereinafter as delimiting diaphragm edges since they delimit the illumination field in the object plane.